ImageLoader.java

package jp.mydns.sys1yagi.android.mockitosample;

import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.view.View;
import android.widget.ImageView;

public class ImageLoader {
  @SuppressWarnings("rawtypes")
  public void loadImage(final ImageView imageView, String imageUrl) {
    Object maybeTask = imageView.getTag();
    if (maybeTask != null) {
      if (maybeTask instanceof AsyncTask) {
        ((AsyncTask) maybeTask).cancel(true);
      }
    }
    AsyncTask<String, Void, Bitmap> task = new AsyncTask<String, Void, Bitmap>() {
      @Override
      protected Bitmap doInBackground(String... params) {
        try {
          return BitmapFactory.decodeStream(new URL(params[0])
              .openStream());
        } catch (MalformedURLException e) {
          e.printStackTrace();
        } catch (IOException e) {
          e.printStackTrace();
        }
        return null;
      }
      protected void onPostExecute(Bitmap result) {
        imageView.setTag(null);
        if (imageView != null && !isCancelled()) {
          imageView.setVisibility(View.VISIBLE);
          imageView.setImageBitmap(result);
        }
      };
    }.execute(imageUrl);
    imageView.setTag(task);
  }

  @SuppressWarnings("rawtypes")
  public void cancel(ImageView imageView) {
    Object maybeTask = imageView.getTag();
    if (maybeTask != null) {
      if (maybeTask instanceof AsyncTask) {
        ((AsyncTask) maybeTask).cancel(true);
      }
    }
  }
}

PreviewActivity

package jp.mydns.sys1yagi.android.mockitosample;

import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.widget.ImageView;

public class PreviewActivity extends FragmentActivity {
  public static final String EXTRA_URL = "url";

  private ImageView mImageView;
  private ImageLoader mImageLoader = new ImageLoader();
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_preview);
    mImageView = (ImageView)findViewById(R.id.image);
    String url = getIntent().getStringExtra(EXTRA_URL);
    mImageLoader.loadImage(mImageView, url);
  }

  @Override
  protected void onResume() {
    super.onResume();
  }
  
  @Override
  protected void onPause() {
    super.onPause();
    mImageLoader.cancel(mImageView);
  }
}

PreviewActivityTest.java

package jp.mydns.sys1yagi.android.mockitosample;

import static org.mockito.Matchers.any;
import static org.mockito.Matchers.anyString;
import static org.mockito.Matchers.eq;
import static org.mockito.Mockito.doNothing;
import static org.mockito.Mockito.verify;

import org.mockito.InjectMocks;
import org.mockito.MockitoAnnotations;
import org.mockito.Spy;

import android.app.Activity;
import android.content.Intent;
import android.test.ActivityUnitTestCase;
import android.widget.ImageView;

public class PreviewActivityTest extends ActivityUnitTestCase<PreviewActivity> {
  @Spy
  private ImageLoader mImageLoader = new ImageLoader();

  @InjectMocks
  private PreviewActivity mPreviewActivity;
  
  public PreviewActivityTest() {
    super(PreviewActivity.class);
  }

  @Override
  protected void setUp() throws Exception {
    super.setUp();
    System.setProperty("dexmaker.dexcache", getInstrumentation()
        .getTargetContext().getCacheDir().getPath());
  }

  @Override
  protected void setActivity(Activity testActivity) {
    super.setActivity(testActivity);
    mPreviewActivity = (PreviewActivity)testActivity;
    MockitoAnnotations.initMocks(this);
  }

  public void testActivity() {
    Intent intent = new Intent();
    String testString = "test";
    intent.putExtra(PreviewActivity.EXTRA_URL, testString);
    startActivity(intent, null, null);
    
    doNothing().when(mImageLoader).loadImage((ImageView) any(), anyString());
    
    getInstrumentation().callActivityOnResume(getActivity());

    verify(mImageLoader).loadImage((ImageView) any(), eq(testString));
  }
}